As I'm new at work, I've never had the misfortune of filling out one of the "timesheets" until a very short time ago. Disastrous. It's an Excel file that has a VERY PRECISE set of formulas, all the dates must be entered manually, etc.
Time to learn how to use the Excel::* modules, I believe.
I'm fiddling around with AI::Expertsystem::Simple, partly because I think I'll do better having a little experience with XML now, and partly because I have need of something that can parse rules.
I haven't quite reached the point where I'm interested enough to learn the API for the Timex dev kit, nor am I hampered by the software provided to the point that I feel I need to break free. I consider it a testament to the software's design that I haven't broken it significantly or found a huge, irritating limitation. I never seem to run out of good stuff to say about the watch, by gum.
I'm still hoping that I can learn enough about the API to make the watch usable as a control device for my wearable computer (once it's built), but that's probably at least a few years off for now.